Nashrieh Shimi va Mohandesi Shimi Iran
Year:2001 | Volume:20 | Issue:2|Papers Count:7

In order to investigate to effective factors influenced the droplet dispersion bed composed in separation zone of an extraction column, a Rotating Disc Contactor (RDC) was designed, and then constructed. The commonly used chemical systems were applied in the absence of any mass transfer operation. In all the experiments, distilled water was the continuous phase and the organic phase consisted of one of the Toluene, n-Heptane and MIBK respectively, was the dispersed phase. The important experimental results are: The inlet continuous phase flow rate had no distinct effect on dispersion bed height and its related average holdup, but any increasement of inlet dispersed phase throughput caused them to increase. Furthermore, allowing the central shaft of column to rotate faster resulted an increasement in the bed holdup. Also, the drop phase throughput had a positive effect on all that variables.      

This paper introduces a new method for the representation of system's tree structure and main tree operations. In this method, each system is viewed as a person who has a parent and several brothers and a unique identifying number. Operations such as adding or removing a sub-tree and other main operations on tree structures are represented mathematically. At the end, the proposed method is implemented for the representation of a typical processing system's tree structure.    

Increase fresh water consumption and wastewater generation in beet sugar mill consequently, will increase both capital and operating costs for effluent treatment system. In this paper, we present water and wastewater minimization in beet sugar mill' through water pinch technology that can help minimize wastewater production and lower treatment costs.      

Recent research shows that how we can find the design of the liquid-liquid continuous settlers (particularly the height of the dispersion) from experimental batch data. Thus we don't need to pilot plant experimental work which could be expensive. Of course in addition to batch settler, there is unsteady-state condition in continuous settler if we change the throughput. Because the steady-state height of dispersion bed changes with throughput. Increase of the throughput can be result to flooding. Therefore it is very important to know the relation between the throughput and the dispersion height to design of the steady-state settler. Some of the researchers have presented the models to relate the height and the throughput, but unfortunately some of the models don't fit the experimental data. In this paper we have presented the results of our experimental work for fourteen different system and investigated the relation between the throughput and the height for these systems.  

Using the experimental data obtained from two RDC columns at two different sizes (7.62 & 21.9 cm) and one PSE column with 21.5 cm size, the effect of axial mixing on the performance of these columns was studied. Comparison between the experimental and theoretical (neglecting the axial mixing) number of transfor units indicates that, this effect in PSE columns is more than RDC columns (400% & 200% respectively). These results show that this effect can increase the height of the PSE column up to 4 times for a specific efficiency. Also the results show that this effect is more in law interfacial tension systems, which shows no need of application of agitation facilities when these systems are used.    

Ablation plays key role in most mathematical models describing the combustion of solid materials. Ablation has previously been applied to describe the melting of icebergs but have recently. Used thermal degradation of solids when exposed to thermal radiation. In ablation process two fundamental assumptions are considered; first, the mass loss is from the surface and the second, surface temperature during the mass loss period remains constant. In present work a mathematical model is given to predict the mass loss of the solid materials such as polyethylene when exposed to thermal radiation in cone calorimeter experiments. The influence of convection and radiation heat loss is studied on the ablation model.